Automatic load control for a reversible heat pump and air conditioner



Aug. 16, 1955 R. L. RHODES 2,715,317

AUTOMATIC LOAD CONTROL FOR A REVERSIBLE HEAT PUMP AND AIR CONDITIONER Filed Jan. 3, 1955 2 Sheets-Sheet 1 l 6 $75 rem METER! IN VEN TOR. EOZerKLfi/wdeS,

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United States Patent ()ffice 2,715,317 Patented Aug. 16, 1955 AUTONIATIC LOAD CONTROL FOR A REVERSIBLE HEAT PUMP AND AIR CONDITIONER Robert L. Rhodes, St. Petersburg, Fla.

Application January 3, 1955, Serial No. 479,396

Claims. (Cl. 62-3) This invention relates to a heat pump or air conditioner, and more particularly to a control system for a heat pump or air conditioning assembly.

The object of the invention is to provide a load control system whereby the output of the heat pump or air conditioner can be limited by decreasing the amount of re- I frigerant in the system.

Another object of the invention is to provide an automatic load control for a reversible heat pump which will provide unidirectional refrigerant flow through a metering system and whereby the efiective refrigerant charge in the system will be varied automatically to compensate for temperature variations to thereby insure high output over all design temperature conditions.

A further object of the invention is to provide an automatic load control for a reversible heat pump or air conditioner which is extremely simple and inexpensive to manufacture.

Other objects and advantages will be apparent during the course of the following description.

In the accompanying drawings, forming a part of this application, and in which like numerals are used to designate like parts throughout the same:

Figure 1 is a schematic showing of the automatic load control of the present invention.

Figure 2 is a view similar to Figure 1 but showing the valve shifted to a different position.

Referring in detail to the drawings, the numeral designates a refrigeration compressor of conventional construction, and extending from the compressor 10 is a first conduit 8 which serves to convey the refrigerant from the compressor 16. The conduit 8 may have a check valve 12 arranged therein. A portion of a conduit 11 is shaped to define a coil 14 which may have fins 15 thereon, and a fan 16 is driven by a motor 17. A T-fitting 18 serves to connect the conduit 11 to second and third conduits 19 and 2G. The second conduit 19 has a pair of oppositely acting or oppositely opening check valves 22 and 23 arranged therein, while the other or third conduit also has a pair of oppositely acting check valves 24 and 25 interposed therein. A branch line or conduit 21 interconnects the pair of conduits 19 and 20 together.

A fourth conduit 27 is connected to a T-fitting 26 which communicates with the conduits 19 and 20 and the fourth conduit 27 may have a coil formation 28 therein. The coil formation 28 may include fins 29 and arranged contiguous thereto is a blower or fan 30 which is operated by a motor 31 of conventional construction. The short conduit 9 may be provided with a check valve 32 adjacent the compressor 10.

Extending from the branch line 21 is a fifth conduit 33 which has a solenoid operated valve 34 therein. A sixth conduit 37 is arranged in engagement with a fitting 36, and the sixth conduit 37 has a flow restrictor arranged therein. A line or conduit 39 leads from a fitting 38 to a tank or receiver 40 and the tank 40 may have gaseous or vapor refrigerant 41 therein and liquid refrigerant 42 below thevapor 41.

The valve 34 may be opened and closed by means of a solenoid 43 which can be connected to a switch 44 by means of a wire 45. A Wire 46 also connects the solenoid 43 to a power line 47, and one of the wires 48 of the power input is connected to the switch 44.

A metering system 49 is arranged in the branch line 21. A valve mechanism 59 is arranged in engagement with the conduits 1.1 and 27, and the valve 50 includes a stationary casing 51 that has a movable core 52 rotatably arranged therein. The core 52 includes a pair of curved passageways 53 and 54 that are mounted for movement into and out of registry with the sections of the conduits 11 and 27'.

The conduits 27 and 11 lead to the valve 50. Also extending from the valve 50 are conduits or lines 8 and 9 which are connected to the compressor 10 through the medium of the check valves 12 and 32.

From the foregoing it is apparent that there has been provided an automatic load control for reversible heat pumps which will provide unidirectional refrigerant flow through the flow metering system such as strainers, driers, high side floats, or other devices requiring unidirectional flow. The present invention will also automatically vary the effective refrigerant charge in the system to compensate for temperature variations and will insure high output over all design temperature conditions. The assembly may also be used to decrease the output of the machine if the compressor cycling is not desired for temperature and humidity control. The unidirectional flow is obtained through the use of the four check valves 22, 23, 24 and 25. With the valve 5% set as shown in Figure 1, the valves 22 and 25 permit the flow of refrigerant through the systern while the valves 23 and 24 block the flow around the control. in the second condition as shown in Figure 2, when the four way valve 5b is turned as indicated, then the valves 23 and 24 permit the flow through the metering system 49, while the valves 22 and 25 prevent the fluid from bypassing the metering system 49.

The control switch 44 may be pressure, temperature, or electrically actuated and the switch 44, solenoid valve 34, receiver tank 49 and fiow restrictor 35 are used for controlling the effective fluid in the system. Thus, when a decrease in output is required, the control switch 44 energizes the solenoid 43 and this permits fluid to flow from the high pressure side of the metering system into the receiver 40. The receiver must be located near the outside coil 28 so that its temperature and pressure will be lower than the high pressure side of the fiow metering system and higher than the low pressure side of the metering system. The restrictor 35 permits refrigerant to slowly return to the low pressure side of the machine and again build up the output by increasing the effective charge in the system after the output has been sufiiciently reduced to allow the control switch 44 to open. When sufficient refrigerant is returned to the system from the receiver 40, the cycle will be repeated.

The system of output control of the present invention is also effective if the high pressure is taken from the refrigerant compressor outlet and the restrictor 35 is connected to the compressor inlet.

The present invention is not a new type of heat pump, but is a better load control system for heat pumps and air conditioning equipment. Broadly the present invention is such that the output of an air conditioner can be limited by decreasing the amount of refrigerant in the system and the automatic control of the amount of refrigerant in the system therefore controls the output. The receiver 40 contains a supply of refrigerant partially liquid 42, and part in the vapor state which is indicated by the numeral 41 and this refrigerant is fed into the system through the restrictor 35 or withdrawn from the system through the solenoid valve 34 as required for control.

Since the receiver 40 is located in outside air the pressure, due to temperature in the receiver 40, will always be lower than the high pressure side of the system metering device 49 and higher than the low pressure side so that flow will always be in the direction indicated.

Since the solenoid valve 34 is connected to the high pressure side of the system metering device, there will be no reverse flow of fluid through the metering device. The four check valves 22, 23, 24 and 25 insure that there will be unidirectional flow through the metering device 49. The control switch 44 may be eliminated when a suitable electrical temperature or pressure control valve is available to replace the solenoid valve 34. It is to be understood that any suitable type of four-way valve can be used for the valve 50 and although the drawings illustrate a rotary valve 50, other types can also be used. The check valves 12 and 32 are positioned inside of the compressor and form part of the compressor.

The high pressure side of the system includes all conduits and components through which the refrigerant flows, between the compressor outlet and the metering system 49. The low pressure side of the system includes all conduits and components through which the refrigerant flows, between the metering system 49 and the inlet of the compressor 10.

The metering system or device 49 is a restriction to the flow of refrigerant necessary to maintain a pressure differential suflicient to cause the refrigerant to condense to the liquid state in the high pressure, high temperature side of the system and to vaporize in the low pressure, low temperature side of the system. There are several metering devices of conventional construction which may be used with the present invention and as for example a capillary tube type can be used if a high temperature is to be maintained by the high side coil, and this also permits subcooling of the liquid in the high side coil and can be used in heat exchange relation with the conduit 9 for added subcooling. The capillary tube is a relatively long tube of small diameter which is of a size so that fluid friction will maintain the required pressure difference between the high and low pressure sides of the system.

A float operated valve may be used for passing liquid from the high to the low pressure side of the system as fast as it is condensed. The high side float may give higher efficiency as it permits the machine to operate against the lowest possible high side pressure if cooling is the primary use of the machine. Any suitable type of metering device 49 can be used in the present invention. The arrows shown by the conduits or lines show the direction of refrigerant flow in the system and are used as an aid in tracing the cycle. The flow restrictor 35 prevents excessive fluid from bypassing the metering device 49 when the solenoid valve 34 is open, and the restrictor 35 also determines the time required to recharge the system to, the overload point and the frequency of operation of the control.

In Figure l the heating cycle refrigerant movement is illustrated. Thus, the compressor 10 reduces the vapor pressure in the coil 28 through conduit 27, four-way valve 50 and conduit 9. This causes the liquid refrigerant in coil 28 to vaporize at a low temperature and absorb heat from the outside air. This vapor flowing to the compressor 10 through the aforementioned components is compressed to a high pressure and consequent high temperature. This high temperature vapor flows through conduit 8, four-Way valve 50, and conduit 11 into coil 14 in the area to be heated. As the temperature of the vapor is reduced in the coil 14 it condenses to liquid and gives up the heat of vaporization which it absorbed in the coil 28, plus the heat of compression. The liquid refrigerant then flows from the coil 15 through the conduit 11, T-fitting 18, conduit 19, check valve 22, and conduit 21 to the metering system 49 and flow around the metering system is blocked by the check valves 23 and 24. The metering system consists of any component requiring unidirectional flow (strainer, drier, etc.) and a pressure reducing device (high side float, capillary tube or the like). Flow through the metering system reduces the pressure on the liquid and lowers the vaporizing temperature. The liquid flows through the conduit 20, check valve 25, T-fitting 26, and conduit 27 to the outside coil 28. The liquid absorbs the heat of vaporization in the coil 28 from the outside air and the cycle is continuously repeated.

Referring to Figures 1 and 2 there is illustrated the refrigerant movement for automatic load control action. Thus, when conditions require that the output of the machine be reduced, the control switch 44 energizes the solenoid 43, which opens the valve 34., This permits fluid to flow through the conduit 33, valve 34, T-fitting 38 and conduit 39 into the receiver tank 40, the restrictor preventing excessive flow through the conduit 37. The resulting reduction of fluid in the coil 14 or coil 28, depending upon what type of metering device is used, lowers the output of the machine. When the reduction of output is no longer required the control switch 44 allows the solenoid valve 34 to close. Fluid again slowly returns to the system from the receiver through the conduit 39, T-fltting 38, conduit 37, restrictor 35 and fitting 36. This returning fluid again builds up in coil 14'or 28 until the overload condition again exists and the cycle is repeated.

The cooling cycle as illustrated in Figure 2 and the action of the machine on the cooling cycle of Figure 2 is similar to the action of Figure 1, except that Figure 1 shows the heating cycle and except for the following differcnces. The four-way valve is thrown to direct the high pressure (hot) vapor from the compressor 1% to the outside coil 28 and the cold low pressure vapor from the inside coil 14 to the compressor 10. This reverses the direction of fluid flow through the systemexcept where unidirectional flow is provided by the four check valves 22, 23, 24 and 25. Fluid now flows through the check valves 23 and 24 while valves 22 and 25 block flow around the controls.

The advantages of the system of the present invention are that there will be provided an efficient and economical method of providing unidirectional fluid flow for a strainer, drier, liquid receiver, and/or other components which require unidirectional flow when used in a reversible heat pump. Further, there is provided a method of automatically varying the effective refrigerant charge in a system for the purpose of controlling the output of the machine, and there is also provided a method of using a liquid receiver in a system that uses a high side float or capillary tube expansion device to supply make up fluid for small refrigerant leaks. The present invention also provides a method of limiting the power required for the compressor, the high side pressure, or the high side temperature, depending upon how the control switch is activated. Furthermore, the present invention can be used to reduce the output of the machine instead of cycling the compressor on and off for humidity control or other conditions where cycling the compressor is undesirable.

I claim:

1. In combination, a refrigerant compressor, a valve mechanism connected to said compressor, a first conduit extending from said valve mechanism, a portion of said first conduit being shaped to define a coil, 2. first T-fitting connected to said first conduit, a second and third con duit connected to said T-fitting, a pair of oppositely opening check spaced apart valves interposed in each of said second and third conduits, a branch line interconnecting said second and third conduits together and joined to said second and third conduit at the space intermediate the respective pairs of valves and having a metering device therein, a second T-fitting connected to the junction of said second and third conduits, a fourth conduit extending from said second T-fitting to said valve mechanism, a portion of said fourth conduit defining a coil, a fifth conduit connected to said branch line at a point intermediate the second conduit and said metering device, a sixth conduit connected to said branch line at the opposite side of the metering device from said fifth conduit and said sixth conduit being also in communication With said third conduit, and a tank communicating with said fifth and sixth conduits.

2. The structure as defined in claim 1, and further including a valve arranged in said fifth conduit.

3. The structure as defined in claim 1, and further including a valve arranged in said fifth conduit, and a solenoid and switch for controlling said last named valve.

4. The structure as defined in claim 1, and further including a flow restrictor arranged in said sixth conduit.

5. In combination, a refrigerant compressor, a valve mechanism connected to said compressor, a first conduit extending from said valve mechanism, a portion of said first conduit being shaped to define a coil, a first fitting connected to said first conduit, a second and third conduit connected to said fitting, a pair of spaced apart valves interposed in each of said second and third conduits, a branch line interconnecting said second and third conduits together and joined to said second and third coriduit at the space intermediate the respective pairs of valves and having a metering device therein, a second fitting connected to the junction of said second and third conduits, a fourth conduit extending from said second fitting to said valve mechanism, a portion of said fourth conduit defining a coil, a fifth conduit connected to said branch line at a point intermediate the second conduit and said metering device, a sixth conduit connected to said branch line at the opposite side of the metering device from said fifth conduit and said sixth conduit being also in communication with said third conduit, and a tank communicating With said fifth and sixth conduits.

References Cited in the file of this patent UNITED STATES PATENTS 2,066,161 Roessler Dec. 29, 1936 2,276,814 Zwickl Mar. 17, 1942 2,359,595 Urban Oct. 3, 1944 

